In vascular catheterization procedures it often is necessary for the physician to use different catheters in the diagnosis or treatment of a particular blood vessel. For example, when performing a coronary angiographic study, a physician commonly will use a series of catheters, to be inserted into the patient. Each of the catheters is provided with a different shape, size or configuration suited for a specific purpose. Angiographic studies typically include the use of at least three cardiac catheters including a right coronary artery catheter, left coronary artery catheter and a pigtail catheter. The three catheters each have different shapes and configurations at their distal tips. The right and left coronary artery catheters are shaped to facilitate placement of their distal outlet tips at the entries to the right and left coronary arteries, respectively. The pigtail catheter is provided with a special pigtail-shaped tip intended to reduce trauma as the catheter is advanced through the patient's tricuspid valve into the ventricle for ventricular studies. By way of further example, other types of catheters may include balloon dilatation catheters which are intended to be placed within a stenosed portion of an artery and then inflated under high pressure to expand the lumen of the artery so as to improve blood flow through the artery. In some dilatation procedures it may be desirable to use a series of dilatation catheters having different sizes or balloon configurations.
It has long been common practice in the placement of catheters to use a guide wire which is placed in the patient's artery and which is receivable in lumen of the catheter. With a guide wire in place, a catheter can be advanced over the guide wire and thereby guided to the intended vascular site. The guide wire serves to center the catheter within the blood vessel and reduces the risk of trauma to the blood vessel by the advancing catheter. The use of a guide wire reduces the risk that the distal end of the catheter might become caught on the inner surface of the blood vessel lumen. The use of a guide wire also enables the catheter to be advanced through the blood vessel relatively quickly, thereby reducing the time required for the procedure.
A standard guide wire typically is slightly longer than the catheter with which it is to be used. For example, with an angiographic catheter of the order of 130 centimeters long, the guide wire typically may be of the order of 145-175 centimeters long. When the catheter is in place over the guide wire, a relatively short portion of the guide wire protrudes proximally from the catheter. That enables the guide wire to be manipulated, if desired, from its proximal, protruding end. In that regard, it may be noted that the guide wire may be a steerable construction in which a bend is formed in its distal tip and the direction in which the bent distal tip extends it controlled by rotating the guide wire from its proximal end. For example, the guide wire may be of the type described in U.S. patent application Ser. No. 421,315 filed Sept. 22, 1982.
When it is necessary to change catheters, it usually is preferred that the catheter be removed in a manner which enables a guide wire to remain in place in the blood vessel so that the next succeeding catheter in the procedure can be inserted into the blood vessel, over the guide wire, and will be guided to the intended site in the blood vessel. In order to maintain a guide wire in place while withdrawing the catheter, the guide wire must be gripped at its proximal end to prevent it from being pulled out of the blood vessel together with the catheter. The catheter, however, is longer than the proximal portion of the guide wire which protrudes out of the patient. Thus, before the catheter is fully withdrawn it completely covers the proximally extending end of the guide wire. As a result, there is no means by which a standard guide wire can be held in place to prevent it from being withdrawn together with the catheter. If, as is often the case, it is desired to place the next succeeding catheter by advancing it over a guidewire, a new, longer guide wire is inserted in to the blood vessel and advanced into a position to provide a guide for the next catheter.
It is recognized generally as undesirable to insert, advance and withdraw a series of guide wires through a patient's blood vessels. To do so greatly increases the risk of trauma and puncture to the patient and also extends the duration of the procedure. It also requires exposure of the patient to additional radiation because of the additional fluoroscopy which would be required to place the successive guide wires In order to reduce the risk of puncture or trauma it has become a long time practice to use an exchange wire when performing catheter exchanges. The exchange wire typically is about 300 centimeters long, much longer than the typical standard guide wire. The structure of the standard and exchange wires typically is the same except for the length. The additional length of the exchange wire results in a long proximally protruding portion which is longer than the catheter to be removed. When a catheter is removed some part of the proximally extending portion of the exchange wire will always be exposed to provide a means by which the exchange wire can be gripped and its position in the blood vessel maintained. Use of the exchange wire reduces the risk of trauma to the patient because it is placed while the first catheter remains in the patient. Thus, the procedure involves initially, removal of the standard guide wire from the catheter while the catheter remains in place in the patient. Then the exchange wire is advanced through the catheter to replace the original guide wire. Because the exchange wire is guided through the patient's blood vessel by the first catheter, it does not contact the lumen of the blood vessel except, perhaps, for a small portion which protruded distally of the first catheter. The original catheter then is withdrawn over the exchange wire, which is maintained in place in the blood vessel. The next succeeding catheter then can be inserted into the patient over the exchange wire.
The foregoing system and technique of using a long exchange wire has been conventional practice for many years. The use of an exchange wire during catheter exchanges, however, is not free from difficulty. The proximally extending end of the exchange wire is quite long and cannot be manipulated easily, should it be desired to manipulate the distal end of the exchange wire. Additionally, the placement of the exchange wire must be performed under fluoroscopy to assure that it is placed properly in the patient's blood vessel. The use of an exchange wire also adds to the time and the complexity of the procedure. Notwithstanding these difficulties, the use of exchange wires has continued to be common practice in making catheter exchanges.
It is among the general objects of the invention to provide an improved guide wire system and technique by which catheter exchanges can be performed without the use of separate exchange wire and in a manner which avoids the foregoing and other difficulties